Method and device for fuel injection in a combustion engine

ABSTRACT

The invention concerns a method by combustion in an internal combustion engine, for example a direct injected diesel engine, in which the fuel injection is done with during the injection changing direction to avoid injection into an already fuel rich location and a device for fuel injection in an internal combustion engine in which the injector is provided with an injector nozzle (1), that is arranged to spray a fuel spray (23) through at least one hole (311) into the engine combustion chamber and the injection is arranged to be done with during the injection changing direction to avoid injection in an already fuel rich location.

TECHNICAL FIELD

The invention is related to the field of internal combustion enginetechnics and especially to a new technics for injection of a fuelmixture in a combustion chamber.

BACKGROUND OF THE INVENTION

In a conventional combustion of a fuel air mixture in a flame in acombustion chamber it is common to spray fuel through a hole in astationary nozzle. The combustion may then be a so called diffusionflame. The combustion of a diffusion flame is exemplified by thecombustion in a diesel engine.

In a diffusion flame, the combustion is achieved by diffusion, that ismolecular transportation mainly through turbulence, of fuel vapour fromthe interior of the flame and diffusion of oxygen from outside to theflame front. Because of the continues injection to the flame centre, ahigh concentration of fuel is maintained in the already oxygen lackingflame centre. In the flame centre with nearest surroundings sootformation is taking place as an intermediate step in the combustionbecause of high temperature and lack of oxygen.

In the outskirts of the flame where the oxygen is added, the highesttemperatures is maintained where the mixture ratio is near tostoichiometric. In the locations with the highest temperatures, most ofthe NOx formation is taking place. A certain air entrainment occurs intothe flame centre, but the amount is far to little for completecombustion.

The development of the combustion system is normally achieved byinfluencing the injection pressure, change of the number of holes, byinfluencing the air movement and combustion chamber geometry. All theseearlier known systems are however based on injecting the fuel mixture ina combustion chamber in stationary directions, that is where it after aninitial process, a lack of oxygen quickly develops in the direction ofinjections.

The technical report SAE950081 describes an injector with variable holearea. The holes is here doing an axial movement. The movement is onlytaking place during the opening phase and the movement does not give thewanted effect. This type of injector with the holes located in theinjector needle should enable an in the injector built in turning andaxial movement mechanism.

PURPOSE OF THE INVENTION

The purpose of the presented invention is to solve the problem of lackof oxygen, soot- and NOx-formation in conjunction with fuel injectionwith conventional practice and devices in conjunction with combustion ina combustion chamber.

SUMMARY OF THE INVENTION

This purpose is achieved by a method and device according to followingpatent claims, where the injection is taking place with varyingdirection during the injection event. Thus the purpose of the presentedinvention is to achieve a method and device witch enables a positionchanging injection of a fuel mixture into a combustion chamber withfeatures which are described of the following patent claims.

SHORT DESCRIPTION OF THE DRAWINGS

The invention will now be described in more detail with notationsaccording to attached drawing figures.

FIG. 1 shows an axial section through a first design of a deviceaccording to the invention.

FIG. 2 shows a diagram over revolution angle and revolving speed as afunction of the crank angle for a device according to the invention.

FIG. 3 shows a diagram over revolution angle and torque as a function ofthe crank angle for a device according to the invention.

FIG. 4 shows an axial section through a second design of a deviceaccording to the invention.

FIG. 5 shows an axial section through a third design of a deviceaccording to the invention.

DESCRIPTION OF THE INVENTION

The following description applies to a direct injected diesel engine,but the invention is applicable on all similar combustion systems.

The invention concerns a system for combustion where the injectioncontinuously changes direction which avoids to spray into a alreadyoxygen lacking flame centre.

One from NOx formation view desirable type of combustion is premixedlean combustion. The lean combustion is also beneficial from sootformation view. The diesel engine is always operating lean in average.Because the injection always takes place in a constant direction,inhomogenous conditions with fuel rich locations and intermediate zoneswithout fuel and combustion.

The combustion in a diesel engine starts as premixed combustion with aunwanted fast pressure increase rate. During the ignition delay, fuelhas accumulated in a limited volume with the result that a big volumehas near stoichiometric mixture strength with following fast combustion.By during the ignition delay distributing fuel in a larger volume byinjecting in different directions, an in average leaner mixture can beachieved. The system can be optimised for mixing conditions with a bigportion of lean mixture with following smooth combustion speed, low NOxand soot formation.

After the ignition delay temperature and pressure increase occurs in thehole combustion chamber. The largest temperature increase occurs inzones where fuel has been combusted. The fuel has ignition delay alsoafter that the combustion has started, but with the higher temperatures,the ignition delay is shorter. By increasing the mixing speed with theaid of increasing the injection pressure, it can be sought afterconditions which also during the ignition delay after start ofcombustion can mix to lean before the combustion starts. Through thechanging injection direction the injection will take place in colderzones (where no combustion has taken place), thus the time for mixingbefore start of combustion of the latest injected fuel increases. Thesystem according to the invention has the potential to mix to leanbefore the combustion. Under all circumstances the new system givescompletely new air movements induced by the injection in differentdirections, which enables optimising for a more environmental friendlycombustion compared to what can be achieved with a stationary injector.

The diesel engine show gradual decreasing combustion rate after the endof injection. This slow termination of the combustion depends of thatthe remaining soot clouds from the centres of the fuel sprays have longdiffusion distances and at the end of the process the total amount ofoxygen is smaller. With the much more intense fuel air mixing withinjection according to the invention, the total combustion time will beshorter with an increase in engine efficiency as result.

To achieve injection in different direction, the injector can be givenan axial movement or a rotational movement or a combination of these.Here is a system with pure rotational movement described.

FIG. 1 shows a first design where the injector is provided with aninjector nozzle 1 which is forward and backward turnable in relation toa cylinder head 5 by providing the injector nozzle 1 with a lowerretaining nut 22 not turnable mounted through a thread in the injectorand sealed against an injector sleeve 2 which is sealed against thecylinder head 5.

The injector sleeve 2 is sealed against the cylinder head through alower seal 3 while the retaining nut 22 for the injector nozzle 1 issealed against the injector sleeve 2 through a piston ring seal 4. Theinjector revolution is lubricated by oil from an oil inlet 6 in thecylinder head 5 and the oil is drained through an oil outlet 8 alsosituated in the cylinder head 5. The injector sleeve 2 is further sealedbetween the oil inlet and the oil outlet through a lubricant seal 7 andfurthermore sealed against the cylinder head in the upper wider partthrough an intermediate seal 10 and a upper seal 13. The injector issupported by a journal bearing in the injector sleeve 2.

In the upper wider part of the injector sleeve 2, the injector nozzle 1is sealed against a cylindrical shaped internal surface in the injectorsleeve 2 through a lower return fuel seal 9 and an upper return fuelseal 12. Through the lower return fuel seal 9 the return fuel isprevented from leak into the lubricating oil which would reduce itsperformance. Through the upper return fuel seal 12 the return fuel isprevented from leaking out of the injector.

The supply of fuel mixture to the injector is achieved through a fuelline 21 inserted radial from the cylinder head 5 into the upper part ofthe injector nozzle 1 and screwed into an in the injector nozzle 1centrally mounted cylindrical shaped swivel 11. The fuel line 21 isprovided with a supply channel 210 which is connected with one in theswivel arranged supply channel 211 which in turn is connected to asupply channel 212 in the injector nozzle 1. The fuel mixture is flowinginto the injector through the supply channel 210, fuel channel 211, thesupply channel 212 and then flow into the combustion chamber when aninjector needle 213 opens. The fuel is distributed into the combustionchamber through hole 311 in the injector nozzle 1 as a fuel spray 23.For leakage fuel a fuel return channel 214 is arranged to allow fuel tobe returned to a around the fuel supply line concentric arranged leakagefuel outlet 20.

The swivel 11 is axially sealed upwards through a plug 19 which is keptin axial tension towards the injector nozzle 1 with the help of an upperretaining nut 14. The retaining nut 14 and thus the injector isconcentric suspended in a tension sleeve 15 through a roller bearing 16.Furthermore a lever 17 is bolted in the retaining nut 14 with the resultthat the lever can revolve the injector nozzle 1 through a cam orequivalent which moves the lever at an alignment surface 18. When theinjector nozzle 1 is turning, the pressure line 21 is retaining theswivel 11 and a relative movement is taking place between the swivel 11and the injector nozzle 1. The fuel line 21 is then displaced in a slitin the injector nozzle 1. This first design of an injector for a directinjected diesel engine is thus designed for turning during the injectionevent.

For such an injector a row of functions must be achieved, like gas sealagainst the combustion chamber, journalling in bearings and cooling ofthe injector, fuel connection and an actuator system to achieve therotating movement.

The gas seal in this first design according to FIG. 1 is achieved by thepiston ring 4 which is located in a groove in the retainer nut 22. Theretainer nut is further movable with a small clearance in the lower part(left in the figure) towards the injector sleeve 2. Into this smallclearance, pressurised oil from the engine lubricating system issupplied through the oil supply channel 6 in the cylinder head 5 (grooveshould be provided to distribute the oil around the circumference). Theoil together with blow by gases is then evacuated through the oil drain8. The lubricant seal 7 of O-ring type divides the pressure side fromthe drain side at the outside of the injector sleeve 2. Throughadjustment of the clearance and the length of the fit between theinjector sleeve 2 and the retainer nut 22, the oil flow and thus thecooling of the injector can be optimised. The fit represents a journalbearing in the lower part of the injector.

Through the limited diameter of the injector, the axial load from thecombustion pressure will be limited. The axial force is carried by theroller bearing 16, which transfer the force to the tension sleeve 15which is threaded into the cylinder head 5. The tension sleeve 15 clampsthe injector sleeve 2 towards the sealing ring 3 which seals between gasand oil at the outside of the injector sleeve.

The fuel connection for the device according to FIG. 1 is designed as ahydraulic swivel 11. The swivel 11 is cross drilled and the ends aredesigned so that the fuel pressure on each side of the swivel 11 is thesame, making it axially force neutral. The leak flow is limited througha tight fit between the swivel 11 and corresponding diameter in theinjector body. A fuel line 21 is screwed into the swivel 11 and providedwith a conical seal. The leakage fuel is let out in the with thepressure line concentric space 20. The leakage fuel area is sealed fromlubricating oil with the intermediate seals 10 of O-ring type and thereturn fuel seals 9, 12.

An alternative fuel supply and drain system is to utilise elasticdeformations in tubing. ±5° torsion of a Ø6 mm pressure tube with thelength 200 mm gives the acceptable shear stress level of ±110 N/mm. By adeliberate shaping of the tubing it should be possible to furtherdecrease the stress level, alternately permit bigger turning angle. Inthat way there is no need for the swivel and the sealing is simplified.

The revolving movement in FIG. 1 is thought to be achieved by actuatingthe lever 17 at the position 18. The engine is thought to have an extracam lobe on the engine cam shaft and a push rod and rocker arm similarto those used for valve opening. The rocker arm is however designed toconvert the pushrod movement which is mainly along the injector axis toa movement perpendicular to the injector axis. The movement istransferred to the lever 17 at the position 18 which also is springloaded for its return stroke.

For disassembly of the injector according to FIG. 1, it is appropriateto remove the tension sleeve 15 and by that the injector can be pulledout provided the fuel line first has been dismounted. For ease ofpulling out the injector sleeve 2 it should be threaded for a pull outtool in the proximity of the oil outlet 8.

To eliminate the risk of loosen the upper retaining nut 14 from therotating movement, the assembly torque is 10-fold the torque from therotating movement.

To prove the plausibility of the concept according to this first designthe following calculated example is presented:

Moment of inertia J=m·r²/2

Study a solid steel injector with simple cylindrical shape. Assumediameter Ø21 mm and the length L=150 mm which gives the mass 0.4 kg. Jthen will be 2.23·10⁻⁵ kgm².

Assume further the engine speed to 2000 rpm.

FIG. 2 shows with these assumptions a diagram over the relation betweenthe turning angle and turning speed for the injector if one assumes themovement to continue for 15 crank angle degrees and be sinus shaped. Therelation according to FIG. 2 then is governed by the formula:

φ=φ_(max)·sin(K ₁ +K ₂·α)

FIG. 3 shows with these assumptions a diagram with the relation betweenthe turning angle and torque from inertia forces for the injector.

The maximum inertia torque according to FIG. 3 is 12.3 Nm. On a lever of60 mm this means 12.3/0.06=205 N force on the lever. Thus a spring isrequired that gives at least 205 N at the turning angle +5 degrees. Theduration of the return stroke to −5 degrees can then go on for a longtime with very low acceleration and low required spring force. To Jshould be added the contribution from the rocker arm and additionalmechanical components.

Lever stroke 60·sin (10)=10.4 mm

Max. injector speed at engine speed 2000 rpm 219 Rad/s

Max. speed at the lever 219·0.06=13.1 m/s

Rotational energy E_(r)=J·ω²/2

E_(r)=2.23E-05·219²/2

E_(r)=0.53 Nm

To be compared with the pumping energy E_(p) at part load, assuming 1000bar and 100 mm³ per injection.

E_(p)=V·P

E_(p)=100E-9·1000E5

E_(p)=10 Nm

In this example the maximum rotational energy is about 5% of the pumpingenergy which can be regarded as acceptable.

FIG. 4 shows a second design of an injector according to the presentinvention. The numerical references in FIG. 4 which corresponds withthat in FIG. 1 described design denote corresponding components whythese components are not described again. As shown by FIG. 4 theinjector nozzle 1 is provided with an injector body 25 which is directlysupported by the roller bearing 16 in the tension sleeve 15. Further theinjector sleeve 2 is provided with an upper seal 24 for the oil outlet8. This upper seal 24 correspond mostly to the intermediate seal 10described for the first design showed in FIG. 1. The roller bearing 16in this second design is in addition sealed on its upper side to preventoil from leaking out.

The injector body 25 is provided with a with the injector sleeveconcentric arranged swivel sleeve 26 turnable connected to the injectorbody 25. The swivel sleeve is provided with external axial grooves 260which allows leakage fuel outside the swivel sleeve 26. The sleeve isfurther rotationally located by not shown gudgeon pins. The injectorbody 25 is then in its upper end opposite the cylinder side, providedwith a rotationally fixed mean for rotation 27 in the shape of a pulleywhich is axially located to the injector body 25 by a nut 28. The pulleyis connected to a not shown mean for rotation which drives the injectorintermittent, continues, oscillating or in an other suitable way atwhich the direction of injection varies in the same way. The swivelsleeve is further axially located in the injector by a tension sleeve 29which is threaded internally inside the injector body 25.

A leakage fuel sleeve 30 is mounted with press fit on a coaxial with theswivel sleeve 26 mounted swivel shaft 32 on which also a leakage fuelreturn line 31 is radial mounted. The leakage fuel sleeve 30 is providedwith axially internal grooves 300 for passage of leakage fuel. Thetension sleeve 29 is then provided with a leakage fuel seal 33 which isarranged to seal between the tension sleeve 29 and the leakage fuelsleeve 30. The swivel shaft 32 is axially fixed through a circlip 34 andis also journalled in bearing in the lower against the cylinder directedend of the injector body 25. The circlip 34 also enables simpledisassembly of the swivel sleeve. Leakage fuel can then flow outside theswivel sleeve 26 in between the swivel shaft 32 and the tension sleeve29, then through the leakage fuel sleeve 30's groove 300 and out throughthe leakage fuel connection 31. In the non rotating swivel shaft 32upper threaded end, a fuel line is mounted which supplies fuel in thecentre of the injector through the swivel shaft 32, out through therotating swivel sleeve 26 and further through the supply channel 212 tothe injector nozzle 1.

FIG. 5 shows a third design of an injector according to presentinvention in which corresponding components are designated withidentical number notations as earlier figures. The injector body 25 isprovided with a centrally placed swivel body 280 which rotates togetherwith the injector body 25 inside the injector sleeve 2 in the same wayas has been shown in the design according to FIG. 4. Axially aligningand rotating with the swivel body 280 is a swivel shaft 32 on which aconnector body 330 is suspended by a journal bearing. The connector body330 enables supply of fuel to the swivel shaft 32 and drain of leakagefuel through drain channels 310, 320 and then to the leakage fuelconnection 31. Axially with the swivel shaft 32 is a cover 340 arrangedin the connector body 330 inside which circlip 34 for disassembly of theswivel shaft is arranged. The design style allows supply of fuelperpendicular in towards the swivel shaft 32 contrary to the designaccording to FIG. 4 where fuel is supplied axially through the swivelshaft 32.

Thus an injector according to the two latest designs which is designedto be driven during the engine revolution can be run with principallyconstant revolution speed. Then the lever 17 in FIG. 1 is exchanged witha gear wheel or pulley as a mean of rotation 27 according to FIGS. 4-5.The fuel inlet and also the return flow is then preferably arrangedthrough the centre of the driving wheel with a swivel sleeve 26respectively swivel body 280 differently shaped compared to the swivel11 in FIG. 1. Then the injector rotational speed can be optimised withregard to the engine load case.

Engines with unit injectors have simplified fuel supply, but the highpumping forces put high demands on the axial bearing. It is advantageousto use the pumping movement to achieve axial movement alternativelyrotational movement. The turning can also be achieved by the aid of theinjection pressure.

Besides a purely mechanical turning mechanism one can think ofmechanisms where the injection pressure or the pumping force (with unitinjectors) creates the movement.

What is claimed is:
 1. Method for fuel injection in a combustion engine, comprising changing direction of fuel injection during injection controlled from outside an injector to avoid injection in an already fuel rich area, wherein direction of fuel injection is changed by rotating an injector during injection, wherein the injector includes a turnable, internal hole carrying element.
 2. Method for fuel injection in a combustion engine, comprising changing direction of fuel injection during injection controlled from outside an injector to avoid injection in an already fuel rich area, wherein the injector rotates at a substantially constant rotational speed, wherein the injector includes a turnable, internal hole carrying element.
 3. Method for fuel injection in a combustion engine, comprising changing direction of fuel injection during injection to avoid injection in an already fuel rich area, wherein direction of fuel injection is changed by rotating an injector during injection, wherein the rotating of the injector causes an elastic deformation of a fuel line.
 4. Method according to claim 3, wherein the injector rotates at a substantially constant rotational speed.
 5. Method according to claim 3, wherein the injector includes a turnable, internal hole carrying element.
 6. Method for fuel injection in a combustion engine, comprising changing direction of fuel injection during injection to avoid injection in an already fuel rich area, wherein direction of fuel injection is changed by rotating an injector during injection, wherein a hydraulic swivel element transfers fuel from a stationary element to a movable element to rotate the injector.
 7. Method according to claim 6, wherein the injector rotates at a substantially constant rotational speed.
 8. Method according to claim 6, wherein the injector includes a turnable, internal hole carrying element.
 9. Method for fuel injection in a combustion engine, comprising changing direction of fuel injection during an injection controlled from outside an injector to avoid injection in an already fuel rich area.
 10. Method according to claim 9, wherein the injector rotates at a substantially constant rotational speed.
 11. Method according to claim 9, wherein the injector includes a turnable, internal hole carrying element.
 12. Method according to claim 9 wherein direction of fuel injection is changed by rotating an injector during the injection.
 13. Method according to claim 12, wherein the injector rotates at a substantially constant speed.
 14. Device for fuel injection in a combustion engine, comprising, an injector with an injector nozzle having at least one hole arranged to inject fuel into a combustion chamber of the engine, the injector being adapted to change a direction of fuel injection during an injection controlled from outside the injector to avoid injection in an already fuel rich area of the combustion chamber.
 15. Device according to claim 13, wherein the injector is provided with an external concentric non-turnable retaining nut including a piston ring seal arranged to seal against a non-turnable injector sleeve in the cylinder head.
 16. Device according to claim 15 wherein the injector is provided with a lever arranged to turn the injector.
 17. Device according to claim 15 wherein the injector includes an injector body including means for rotating the injector.
 18. Device according to claim 15 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 19. Device according to claim 18 wherein the fuel connection coaxial with the swivel shaft.
 20. Device according to claim 15, wherein the injector sleeve includes an oil supply to the cylinder head and an oil outlet from the cylinder head.
 21. Device according to claim 20 wherein the injector is provided with a lever arranged to turn the injector.
 22. Device according to claim 20 wherein the injector includes an injector body including means for rotating the injector.
 23. Device according to claim 20 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 24. Device for fuel injection in a combustion engine, comprising, an injector with an injector nozzle having at least one hole arranged to inject fuel into a combustion chamber of the engine, the injector being adapted to change a direction of fuel injection during an injection to avoid injection in an already fuel rich area of the combustion chamber, wherein the injector is turnably journalled in bearings in an engine cylinder head.
 25. Device according to claim 24, wherein the injector is provided with a lever arranged to turn the injector.
 26. Device according to claim 25 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 27. Device according to claim 25, wherein the injector is provided with a fuel line for fuel supply radially connected to a swivel that is coaxial with and turnably mounted in the injector.
 28. Device according to claim 27 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 29. Device according to claim 27, wherein a fuel return in the injector is connected to a concentrically arranged leakage fuel connection around the fuel line to allow for return fuel.
 30. Device according to claim 29 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 31. Device according to claim 24 wherein the injector includes an injector body including means for rotating the injector.
 32. Device according to claim 31 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 33. Device according to claim 31, wherein the injector body includes a fuel channel and a swivel body is mounted in the injector body and axially aligns with a swivel shaft having a fuel channel, the swivel shaft being concentrically mounted in the injector body so that fuel is supplied to the injector nozzle through the swivel shaft and then through the swivel body.
 34. Device according to claim 33, wherein a connector body is arranged to contain the upper part of the swivel shaft.
 35. Device according to claim 34, wherein the connector body is provided with radial connections for fuel supply and return flow.
 36. Device according to claim 31, wherein a swivel sleeve is disposed in a fuel channel in an injector body and is turnably mounted around a swivel shaft and is provided with a fuel channel, the swivel shaft being concentrically mounted in the injector body, wherein fuel is supplied to the injector nozzle through the swivel shaft and to a leakage fuel connection in the swivel shaft.
 37. Device according to claim 36, wherein the fuel connection coaxial with the swivel shaft.
 38. Device according to claim 36 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 39. Device according to claim 36, wherein the swivel sleeve includes at least one groove located on an outside thereof, the groove allowing leakage fuel to pass around the swivel sleeve to a passage along a periphery of the swivel shaft to the leakage fuel connection.
 40. Device according to claim 39 wherein the swivel sleeve is axially located in the injector by a tension sleeve which is internally fastened in the injector body by threads.
 41. Device according to claim 39 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 42. Device according to claim 39 wherein the fuel connection coaxial with the swivel shaft.
 43. Device according to claim 36 wherein the swivel sleeve is axially located in the injector by a tension sleeve which is internally fastened in the injector body by threads.
 44. Device according to claim 43 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 45. Device according to claim 43 wherein the fuel connection coaxial with the swivel shaft.
 46. Device according to claim 43, a leakage fuel sleeve with axial internal grooves is provided for leakage fuel and is mounted on the swivel shaft, and the tension sleeve is provided with a leakage fuel seal arranged to seal against the leakage fuel sleeve.
 47. Device according to claim 46 wherein the injector includes, on one side thereof, a journal bearing in the injector sleeve and, on another side thereof, is suspended by a roller bearing in a tension sleeve screwed in to the cylinder head.
 48. Device according to claim 46 wherein the fuel connection coaxial with the swivel shaft. 